Report from the Botanical Section. U 



15th December, 1847.— Vice-President in the Chair. 

 Mr. Keddie gave in the following report from the botanical section: — 



" The President, Dr. Walker Arnott, in the chair. The President pre- 

 sented to the Herbarium a collection of exotic ferns, chiefly from the 

 southern part of the peninsula of India and Ceylon. 



" Mr. Gourlie presented 105 species of British and Foreign mosses and 

 jungermannia?, and exhibited the fruit of Madura aurantiaca, from the 

 neighbourhood of Philadelphia, sent by Mr. Gavin Watson. 



" Dr. Walker Arnott gave an account of the characters adopted for the 

 distribution of ferns into genera, accompanied with an historical sketch of 

 this branch of botany. 



"Among the ancients there appeared to be no distinctions except such as 

 Filix mas and Filix fazmina. Bauhin was the first to make any attempt 

 of the kind, and Tournefort in his Institutiones rei herbarice did little more 

 than give figures of Bauhin's genera, which depended chiefly on the form 

 of the fronds. Linnaous, as in every thing else, laid down new principles, 

 with which at this present day we are still working. Sir Jas. E. Smith, 

 in the Turin transactions for 1793, extended LinnaDus's views, and added 

 several new genera indispensable from the multitudes of species discovered 

 since the time of Linnaeus. 



"By none of these was the subject of venation attended to, either to 

 assist in specific or generic characters. The first whose mind seems to 

 have been directed to this subject was Mr. R. Brown of London, who, in 

 one or two genera in his Prod, florae Novce Hollandiw published in 1810, 

 distinctly announced the necessity of introducing new elements ; and these 

 were afterwards brought out more clearly in 1830, in the first volume of 

 Wallich's Plantce rariores f in the description of Matonia, and a short time 

 after in the first part of Horsfield's Plantce Javanicw rariores; but Brown, 

 with that degree of caution which marks the true botanist, is far from 

 asserting that the venation affords in all cases a good generic auxiliary. 

 Presl, however, in Germany, and Mr. John Smith of Kew Gardens, have 

 carried the doctrine of venation to excess ; and finding it useful in some 

 instances for distinguishing genera with a different appearance or habit, 

 have applied it as an universal principle throughout this group of plants. 



"Dr. Walker Arnott then pointed out some genera, to characterize which 

 the venation might be employed with the utmost advantage ; and others, 

 in which the simple and reticulated venation was to be found in the same 

 species, and even in the same specimen. The great error, he observed, 

 lay in forgetting the Linnaaan maxims — l Qua? in uno genere ad genus 

 stabiliendum valent, mini me idem in altcro necessario praestant,' — (Fund. 

 Bot. § 160 ) ; that the character that may suffice for defining one genus 

 may not be good for any other ; and the neglecting the equivalent one, 

 "character Unit v genere, non genus e charactere." He concluded by 

 inc ho a ting s.mio genera, in which the presence or absence of the involucre 



